Synthesis gas mixtures consisting essentially of carbon monoxide and hydrogen are important commercially as a source of hydrogen for hydrogenation reactions, as a method of generating power from otherwise environmentally unacceptable fuel sources, and as a source of feed gas for the synthesis of hydrocarbons, oxygen-containing organic compounds or a ammonia.
The partial combustion of a hydrocarbon fuel with oxygen-enriched air or with relatively pure oxygen to produce carbon monoxide and hydrogen presents unique problems not encountered normally in the feed injector art. It is necessary, for example, to effect very rapid and complete mixing of the reactants, or a substantial fraction of the reactants will be oxidized to carbon dioxide and water. It is also necessary to take special precautions to protect the feed injector from over-heating. Because of the reactivity of oxygen with the metal from which a suitable feed injector may be fabricated, it is extremely important to prevent the feed injector elements from reaching those temperatures at which failure can occur. In this connection, it is desirable that the reaction between the hydrocarbon and oxygen take place outside the feed injector proper. Even though the reaction generally takes place beyond the point of discharge from the feed injector, the feed injector elements are subjected to heating by radiation from the reacting hydrocarbon and oxygen.
Any effective feed injector design can be used to assist the addition or interaction of feedstock and gas in the reactor, such as an annulus-type fuel injector described in U.S. Pat. No. 2,928,460 to Eastman et al., U.S. Pat. No. 4,328,006 to Muenger et al. or U.S. Pat. No. 4,328,008 to Muenger et al which are incorporated herein by reference. Alternatively, the feedstock can be introduced into the upper end of the reactor through a port. Free-oxygen-containing gas is typically introduced at high velocity into the reactor through the fuel injector. By this arrangement the charge materials are intimately mixed within the reaction zone and the oxygen gas stream is prevented from directly impinging on and damaging the reactor walls.
The feed injector is exposed to high temperature during normal operations which exceed the melting point of most metals. The overheating problem is also expected during preheat. The reactor must be preheated to near normal operating temperature to initiate the gasification reaction.
For one or more of the forgoing reasons, the prior art feed injectors are characterized by failure of feed injector elements, particularly by erosion of metal at the feed injector tips even where these elements have been water cooled. Feed injector failure is anticipated. It is desirable that the feed injector be cooled. It is desirable that failures in the feed injector be readily detected. It is desirable that a leak in the feed injector does not result in cooling system failure and subsequent catastrophic feed injector failure. It is desirable that leaks do not allow cooling water to suddenly empty into the reactor. Similarly, it is desirable that leaks do not allow reactor contents leaking into the cooling system to cause catastrophic failure of the cooling system.